Vga gt240 - damage image

I just bought new gt 240 and installed psu 400 w
When plays game for several minutes, screen becomes white (or the color changed) and image become damage.
but it would be returned in any minutes (or i minimized then back to normal) and the problem comes back again.

we purchased 6 vga g240 installed in amd or intel - just the same.
we already changed the computer which run well using another nvidia and installed this vga gt240 - the computer become damage screen (previously not)

also,already update new driver - not take effect too

plz help